Re: [PATCH, libmpx, i386, PR driver/65444] Pass '-z bndplt' when building dynamic objects with MPX

[Ilya Enkovich <enkovich dot gnu at gmail dot com>]

2015-04-06 18:28 GMT+03:00 Jeff Law <law@redhat.com>:
> On 04/06/2015 09:17 AM, Ilya Enkovich wrote:
>>>
>>>
>>> To tell the truth, I can't figure out what this means from a user
>>> perspective.  How does a user know whether the linker option is
>>> being ignored, or if they have a new enough linker?  If the linker
>>> available at configuration time doesn't support the option, does
>>> that mean the option will never be passed and users will never know
>>> that there are gaping holes in the pointer bounds checking?
>>>
>>> My suggestion would be to pass the option unconditionally and make
>>> the documentation say something like
>>
>>
>> This option was rejected.
>
> Right.  There really isn't a good option here because we don't have the
> infrastructure to query the linker's capabilities at link time.
>
> Though I do wonder if we could issue a warning in the case where the
> configure test indicated -z bndplt was not supported.

I thought about such possibility. Just don't see a good place for
that. Probably introduce some WARNING_SPEC which targets may define to
issue a driver warning?

Ilya

>
> It'd obviously mean a link warning every time an end user tried to use that
> toolchain to create a DSO or executable with MPX protection.  But that may
> be better than silently leaving some code unprotected.
>
>
> Jeff
>